Image is broken preview and uploaded state in uploading sequence+example

After small investigation about problem i've realized that when i'm upload an image (example i.png) wagn search for filename i_medium.png after upload. Because this handling wagn cannot find i.png both preview and uploaded state.  

If i run this command 

mv ./public/card_images/0000/0007/i.png ./public/card_images/0000/0007/i_medium.png

i'm reaching mentioned file manually.